Introduce rare, valuable "chase items" for a variety of mobs in their loot table, with the intention of diversifying gear selection. The idea is every mob has some sort of jackpot that feels interesting because it's the only way to get that useful item.

This is done well with the exceptional/peerless items that give a small chance for "best in slot" gear with marginal differences, and also the earring slot. Expanding upon this will give people reasons to continue pveing a variety of mobs for certain chase items. Example items can be things that are not craftable, but will diversify how someone would gear themselves.
One example for clarity: An oathliege drops a purple hood that is enchanted with either spell duration, spell magnitude, or mana efficiency. A purple hood is normally not worn by players because it offers no meaningful protections, but with this enchanted hood, it gives the option of a player having a staff enchant on a piece of armor (uncraftable). This can be good for a PvEr to have mana efficiency without needing to enchant many staves that they end up breaking, or a PvPer deciding to have 3 valuable staff enchants at once.
Another example can be weapons that apply minor debuffs on hit (e.g. a fire transmute sword that applies a fire weakness debuff).
A robe/jewelry that makes mobs think you're crouched even while sprinting/jumping around (reduced aggro range)
There are many potential items that could be designed.